Mexican filmmaker Lila Avilés’ sliceof- life second feature, “Tótem,” has an uncanny intimacy, immersing us in the lives of a family as they prepare for a birthday party for one of their members — a party that may well be his last. Tonatiuh (Mateo García Elizondo) is a frail, sick young man who tries hard to rally for the occasion, particularly for the benefit of his 7-year-old daughter Sol …